Seat cushion

ABSTRACT

A seat cushion comprises a relief portion to selectively provide cushioning to a user&#39;s sitz bones received when the user is seated on a seating surface. The selective cushioning provided by the relief portion to the user&#39;s sitz bones can be greater than cushioning provided by the remainder of the seat cushion to portions of the user&#39;s body other than the sitz bones. The relief portion can be in the form of a pair of relief pockets offset to be depressed below the second surface. A resiliency of the relief pockets is different from a resiliency of areas of the second surface surrounding the relief pocket. The first surface and the second surface of the seat cushion can be contoured so as to form a central core, a relief portion substantially surrounding the central core, and an outer portion defined so as to surround the relief portion.

RELATED APPLICATIONS

The present application claims priority to U.S. Provisional Application 62/347,888, filed Jun. 9, 2016, and U.S. Provisional Application 62/410,504 filed Oct. 20, 2016, the entire contents of each of which is hereby incorporated by reference.

BACKGROUND

Traditional sitting postures assumed when using typical office seating such as chairs has, over time, a detrimental impact on an individual's health. Besides encouraging a sedentary lifestyle, traditional seating may create muscular or orthopedic discomfort for a person. A more healthful and active seating postures, such as those provided by the upright active-sitting seat of U.S. 2013/0306831 A1 assigned to the assignee of the present application may be beneficial to a user.

It is generally known that the gluteus maximus muscles, which provide cover to ischial tuberosity (also known as “sitz bones”) in a standing or upright position, do not provide any cover to the sitz bones in the seated position. Further, because weight is frequently placed on the sitz bones while seated, this may cause discomfort to a person.

SUMMARY

In an aspect, this disclosure is directed to a seat cushion, comprising a first surface providing a seating surface to sit on and a second surface opposite to the first surface. The second surface can have a pair of relief pockets. The relief pockets can be offset to be depressed below a plane of the second surface so as to provide cushioning to a user's sitz bones received when the user is seated on the seating surface at a location corresponding to the relief pockets. The second surface can have variable resiliency such that a resiliency of the relief pockets is different from a resiliency of areas of the second surface surrounding the relief pocket.

In another aspect, the first surface and the second surface can be contoured so as to form a central core defined about a seat axis, a relief portion extending around the seat axis so as to substantially surrounding the central core, and an outer portion defined so as to surround the relief portion. The relief portion can be configured to receive and provide cushioning to a user's sitz bones received when the user is seated on the seating surface. The relief portion can be deformable when a user's weight is supported by the seating surface. The deformation of the relief portion can be substantially greater than a deformation of the central core and/or the outer portion when a force equivalent to the user's weight is applied on the central core and/or the outer portion.

In a further aspect, a relief portion can be shaped and sized to selectively provide cushioning to a user's sitz bones received when the user is seated on the seating surface at a location corresponding to the relief portion. The selective cushioning provided by the relief portion to the user's sitz bones can be greater than cushioning provided by the remainder of the seat cushion to portions of the user's body other than the sitz bones that are in contact with the seating surface.

The details of one or more examples are set forth in the accompanying drawings and the description below. Other features, objects, and advantages will be apparent from the description and drawings, and from the claims.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a perspective view of a non-limiting exemplary pivot seat according to an embodiment;

FIG. 2 is a front perspective view of a non-limiting exemplary seat cushion according to an embodiment;

FIG. 3 is a cross-sectional view of the seat cushion of FIG. 2 taken along the plane 3-3;

FIG. 4 is a cross-sectional view of the seat cushion of FIG. 3 taken along the plane 4-4;

FIG. 5A is a cross-sectional view of the seat cushion of FIG. 3 taken along the plane 5-5 showing the relief pockets in the undeformed state;

FIG. 5B is a cross-sectional view of the seat cushion of FIG. 3 taken along the plane 5-5 showing the relief pockets in the deformed state when the user sits on the seat cushion;

FIG. 6 is a front view of the seat cushion of FIG. 2;

FIG. 7 is a bottom view of a seat cushion according to another embodiment; and

FIG. 8 is a bottom perspective view of a portion of the pivot seat of FIG. 1;

FIG. 9 is a bottom elevation view of the portion of the pivot seat illustrated in FIG. 1; and

FIG. 10 is an exploded perspective view of the portion of the pivot seat illustrated in FIG. 1.

FIG. 11 is a front perspective view of a non-limiting exemplary pivot seat according to another embodiment;

FIG. 12 is an exploded perspective view of the pivot seat of FIG. 11;

FIG. 13 is a perspective view of a seat cushion shown in FIG. 11 according to another embodiment;

FIG. 14 is a bottom perspective view of the seat cushion of FIG. 13; and

FIG. 15 is a sectional front view of the seat cushion taken along the sectional plane 15-15.

DETAILED DESCRIPTION

FIG. 1 is a perspective view of a pivot seat 100 according to an embodiment. The embodiment of FIG. 1 includes features that can optionally be provided on the embodiments of FIGS. 2-7 or embodiments of FIGS. 8-10. The pivot seat 100 includes a base 102. The base 102 of the pivot seat 100 is not illustrated in detail in FIG. 1 and is represented as a block, to further focus on the upper portions of the seat. However, any known base 102 suitable for use with (e.g., support) such pivot seats can be used. The seat comprises a pivot post 104 that is pivotable with respect to the base 102 of the seat so as to encourage a more active seating posture. For instance, the seat would pivot toward the front such that when the user sits on the seat, their sitz bones are supported by the relief pockets of the seat cushion 130 on the seat, as will be described further below with respect to FIGS. 2-6. In such cases, the pivot post 104 would shift toward the front, as shown by the dashed lines in FIG. 1. The extent to which the pivot post 104 can pivot can be variable, thereby encouraging the user to assume a wide range of active seating postures so as to permit blood flow to the user's lower body. Such embodiments may further engage and “work” associated muscle groups. The pivot post 104 can be pneumatically adjustable to a suitable height with respect to the base 102.

With continued reference to FIG. 1, the pivot post 104 comprises a first end 108 and a second opposite 110 to the first end 108. The first end 108 of the pivot post 104 is pivotally coupled to the base 102, whereas the second end 110 of the pivot post 104 is coupled to a seat pan 120. The seat pan 120 can be connected to the pivot post 104 by a hinge mechanism 122. Details of the hinge mechanism 122 are provided in the commonly-assigned U.S. Publication No. 2013/0306831 A1 assigned to the assignee of the present application, the disclosure of which is hereby incorporated by reference.

Continuing with FIG. 1, the seat pan 120 can be connected to a seat cushion 130. The seat pan 120 and the seat cushion 130 can have substantially identical surface contours. For instance, the bottom surface of the seat cushion 130 and the top surface of the seat pan 120 can be substantially identical in shape and profile such that the seat pan 120 generally conforms to the shape of the seat cushion 130 (or vice versa). The seat cushion 130 can have a front edge 136 generally aligned with the front edge 138 of the seat pan 120. The front edge 136 of the seat cushion can generally be in contact with at least a portion of the user's legs (e.g., thighs) when a user is seated on the active seating position illustrated in FIG. 1 (dashed lines). The seat cushion 130 can have relief areas sized and shaped so as to provide optimal cushioning to the sitz bones of a person seated on the pivot seat 100 in the active seating posture indicated by the dashed lines in FIG. 1, as will be described further below.

As is apparent, the seat cushion 130 is resilient relative to the seat pan 120 and at least some portions of the seat cushion 130 can flex when a load (a user's body weight) is placed thereon. In some examples, a substantial portion (e.g., greater than about 50% of the area) of the seat cushion 130 can be resilient relative to the seat pan 120. In other examples, the entirety of the seat cushion 130 can be resilient relative to the seat pan 120.

FIG. 2 is a front perspective view of a seat cushion 10 according to an embodiment. The seat cushion 10 while illustrated as being provided on an ergonomic chair, can alternatively be provided on seats such as office chairs, car seats, bicycle seats, and other ergonomic furniture at home, in businesses or public spaces. The seat cushion 10 can be provided on the seat pan 120 (best seen in FIG. 1), and be substantially similar to the seat cushion 130 illustrated in FIG. 1.

With reference to FIG. 2, the seat cushion 10 comprises a first surface 12 on which a user sits. The first surface 12 can be a top surface or any interior surface below the upper most surface. FIG. 3 is a bottom view of the seat cushion 10 of FIG. 2. Referring now to FIG. 3, the seat cushion 10 comprises a second surface 14. The second surface 14 can be a bottom surface or any interior surface spaced apart from and/or opposite to the first surface 14. The second surface 14 comprises a plurality of connectors 16 to interface with a seat pan (e.g., such as seat pan 120 of FIG. 1). Referring to FIG. 3, in the illustrated embodiment, the connectors 16 are buttons extending away from the second surface 14 of the seat cushion 10. The seat pan which receives the seat cushion 10 may have complementary connectors 16 (e.g., recesses at locations corresponding to the buttons 16 of the cushion 10 on the seat pan 120) to receive the seat cushion 10 securely on to the seat pan 120. Once secured, the connectors 16 may reduce relative motion (e.g., sliding) between the seat pan and the seat cushion 10.

With continued reference to FIG. 3, the seat cushion 10 of the present embodiment includes a plurality of ribs 18 recessed from the second surface 14. The ribs 18 are formed during fabrication of the seat cushion 10. As mentioned earlier, the seat cushion 10 of the present embodiment is formed by molding. In one example, the seat cushion 10 may be formed by injection molding a polymer material, such as Ethylene-vinyl acetate (hereinafter, “EVA”) to form the seat cushion 10 of desired shape and size. In such embodiments, the ribs 18 facilitate flow and heat transfer during the injection molding process so as to obtain a seat cushion 10 with desired variable resiliency, as will be described further below. Other details of the injection molding process known in the art are omitted for brevity. As is apparent to one skilled in the art, injection molding EVA results in a closed-cellular foam, thereby providing advantageous properties such as resistance to water seepage and/or microbes (e.g., mold, mildew and bacteria). In some embodiments, the seat cushion 10 is fabricated as a unitary piece, and yet having portions of different resiliency or cushioning properties. Such embodiments may provide comfort to the user (due to absence of seams or ridges on the seating surface), while being durable and cost effective to fabricate.

FIG. 4 is a cross-sectional view of the seat cushion 10 of FIG. 3 taken along the plane 4-4 seen in FIG. 3. As described previously, the seat cushion 10 is fabricated to have selective resiliency so as to provide support to the user seated thereon. For instance, the seat cushion 10 can be designed so as to provide cushioning to a user's sitz bones. Referring back to FIG. 3, the seat cushion 10 according to such embodiments include a pair of relief pockets 20 provided on the second surface 14 at a location corresponding to the location of the sitz bones in an average adult male or female user. The relief pockets 20 can have a size and shape to provide a cushioning effect to the sitz bones received and seated on the first surface 12 of the seat cushion 10, at a lateral and longitudinal location corresponding to the relief pockets 20 (shown in FIG. 1).

Advantageously, the seat cushion 10 according to the present embodiment is molded as a single piece, with variable resiliency at various portions of seat cushion 10, such that different portions of the seat cushion 10 deform at different rates when a force (e.g., body weight) is applied on the seat cushion 10 (e.g., as seen in FIGS. 5A-5B). Referring back to FIG. 4, in an exemplary embodiment, the relief pockets 20 can provide greater cushioning than areas of the second surface 14 (e.g., ribs 18) surrounding the relief pockets 20 when a user sits thereon. In such cases, referring again to FIG. 5B, when the relief pockets 20 deform in response to the user's weight, the deformation of the relief pockets 20 is greater than a deformation of the areas of the second surface 14 surrounding the relief pocket, when a force equivalent to the user's weight is applied on the areas of the second surface 14 surrounding the relief pocket. For instance, the areas surrounding the relief pockets 20 may have negligible deformation relative to the deformation of the relief pockets 20, when the force equivalent to the user's weight is applied on the areas of the second surface 14 surrounding the relief pocket. In some such exemplary embodiments, the user's weight can be in the range of between about 100 pounds and about 300 pounds. As used herein, properties of the seat cushion such as resiliency, softness or cushioning of the relief pockets 20 relative to areas surrounding the relief pockets 20 can be measured and quantified by a surface hardness measuring apparatus such as a durometer. In such cases, the softness or cushioning of the relief pockets 20 measured by the durometer can be greater than those of areas surrounding the relief pockets.

Referring again to FIG. 4, a cross-sectional side view of one of the relief pockets 20 is illustrated. FIG. 4 shows the seat cushion 10 from an inverted side view, with the second surface 14 shown above the first surface 12 for ease of illustration. However, as is apparent to one skilled in the art, the user's weight would act in the direction of the arrow “a” shown in FIG. 4 when the user is seated on the first surface 12. The relief pockets 20 are shaped so as to have a cushioning greater than those of areas surrounding the relief pockets 20. In the illustrated embodiment, the relief pockets 20 can be generally symmetric about a transverse axis 24 of the seat cushion 10 but may be positioned so as to have a greater surface area near the front edge 44 than the back edge 46. The relief pockets 20 have less material (EVA) relative to the surrounding areas 22 such that when the sitz bones apply pressure thereon (e.g., from the first surface 12), the shape of the relief pockets 20 permit bowing (e.g., as shown by dashed lines). While the illustrated embodiment show the relief pockets 20 to have a “kidney” shape, other shapes such as circular, oval and square are also contemplated within the scope of the present disclosure. Such embodiments advantageously permit users with different sitz bone spacing to sit on the seat cushion and experience comparable cushioning.

The relief pockets 20 of some exemplary embodiments may have a “shape memory” configured to permit the relief pockets 20 to support users of different body weights without having to customize the shape and size of the relief pockets 20 for each user. For instance, the relief pockets 20 may have an initial shape (shown by the solid lines in FIG. 3) when the user is not seated on the seating surface, as illustrated in FIG. 3. As mentioned above, the relief pockets 20 have a resiliency such that the relief pockets 20 “bow”, for instance, to the exemplary shape shown by dashed lines 26 in FIG. 4. However, once a user seated in the seating surface rises from the seating surface the relief pockets 20 may return to their initial shape. Such embodiments may permit the seat cushion 10 to provide selective cushioning customized to users of different weights because the seat cushion 10 may return to its initial shape each time after the user's weight is removed. As mentioned above, in such cases, the areas surrounding the relief pockets 20 may have negligible deformation in response to a force equivalent to the user's weight applied thereon.

FIG. 5A-5B illustrate a cross-sectional view of the seat cushion 10 of FIG. 4 taken along the plane 5-5 with and without a force acting on the relief pockets, while FIG. 6 is a front view of the seat cushion 10 of FIG. 2. In some embodiments, the relief pockets 20 are shaped and sized to selectively provide cushioning to the user's sitz bones received when the user is seated on the seating surface at a location corresponding to the relief pockets 20. As mentioned previously, the cushioning provided by the relief pockets 20 to the user's sitz bones is greater than cushioning provided by the remainder of the seat cushion 10 to portions of the user's body other than the sitz bones that are in contact with the seating surface.

Such selective cushioning can be achieved by an appropriate shape and size of the relief pockets 20. In one example, the relief pockets 20 are positioned to span a certain area of the second surface 14 so as to provide selective cushioning. For instance, the relief pockets 20 can occupy an area of between about 5% and about 50% of a total surface area of the second surface 14. Relief pockets 20 sized to occupy less than about 5% of the total surface area of the second surface 14 may not provide adequate cushioning and may be too firm, while relief pockets 20 sized to occupy greater than about 50% of the total surface area of the second surface 14 may result in the rest of the seat cushion 10 deforming more than a desirable amount under the user's body weight and thereby not providing adequate support. In some embodiments, the relief pockets 20 can occupy an area of about 20% for optimal cushioning of the sitz bones while providing adequate support to the remainder of the user's body in contact with the seat cushion 10.

In another example, the relief pockets 20 can be spaced such that the spacing between the two relief pockets 20 are at a certain desired value to provide selective cushioning to the sitz bones. In this example, the spacing is measured between the geometric centers of the two relief pockets 20. For example, the spacing between the relief pockets 20 corresponds to a sitz bone spacing of an adult male or female user such that on average, the user's sitz bones rest generally at the geometric center “c” of the relief pockets 20. In such examples, the geometric centers “c” of the relief pockets can have a spacing 42 of between about 4 inches and about 8 inches, for instance, about 6 inches. However, it is generally known that the spacing between sitz bones in some adult male users may have a standard deviation of up to about one inch toward each other relative to the average sitz bone spacing of adult male users. In such cases, the spacing 42 of the relief pockets 20 can be about 5 inches. Similarly, the spacing between sitz bones in some adult female users may have a standard deviation of up to about one inch away from each other relative to the average sitz bone spacing of adult female users. In such cases, the spacing 42 of the relief pockets 20 can be about 7 inches. Accordingly, the relief pockets 20 can be sized to accommodate a standard deviation of about +/−1 inch in the sitz bone spacing relative to the average sitz bone spacing in adult male and female users.

In such examples, the relief pockets 20 can have a thickness 28 of between about 20% and about 70% of thickness 30 of the seat cushion 10 to provide increased cushioning at locations corresponding to the relief pockets 20. Further, the relief pockets 20 may have a depth 38 of between about 5% and about 50% of an overall depth 48 of the seat cushion 10, and a width 32 of between about 5% and about 50% of an overall width 40 of the seat cushion 10. Such exemplary embodiments with optimal size and spacing of the relief pockets 20 can advantageously accommodate users of different sizes and weight (and corresponding variability in sitz bone spacing).

In the illustrated embodiment, the thickness 30 of the relief pockets 20 gradually varies in the depthwise direction (e.g., along depth 38), as seen in FIG. 3. In other words, the thickness of the relief pocket 20 near the back edge 46 of the seat cushion 10 is greater than the thickness of the relief pocket near the front edge 44 of the seat cushion 10. Further, the thickness 30 of the relief pockets 20 is generally constant along the widthwise direction (e.g., along width 32), as seen in FIGS. 5A and 5B. However, in alternative embodiments, the thickness 30 of the relief pockets 20 can be generally constant in both the depthwise and widthwise directions (e.g., if the relief pockets 20 are hemispherical). Alternatively, the thickness of the relief pockets 20 can be variable along both the depthwise and widthwise directions when relief pockets 20 of other shapes are used. The relief pocket dimensions described herein provide optimal cushioning and selective resiliency as described in various embodiments herein.

Referring back to FIGS. 2 and 4, the relief pockets 20 are positioned in the depthwise direction to be proximal to the front edge 44 than the back edge 46 of the seat cushion 10. For example, the geometric center “c” of the relief pockets 20 may be positioned to the front of the transverse axis 24 of the seat cushion 10. It is worthwhile mentioning that the geometric center of the relief pockets 20 may or may not coincide with the point of minimum thickness. In some examples, if the geometric center does not coincide with the point of minimum thickness of the relief pocket, the point of minimum thickness may be positioned to the front of the transverse axis 24 of the seat cushion 10. Such embodiments permit the user to sit in a more active or neutral sitting posture. For example, seat cushions according to some such embodiments may be suitable for use with an upright active-sitting seat illustrated in FIG. 1, whereby the user sits more toward the front end of the seat (e.g., near edge 138) to reduce some of the discomfort and health hazards associated with traditional seating. Such upright active seats encourage better blood circulation and improve concentration and alertness. Seat cushions illustrated herein can, of course, be used with other seats such as traditional office chairs, car seats, bicycle seats, household furniture and the like.

FIG. 7 is a bottom view of a seat cushion 200 according to another embodiment. The embodiment of FIG. 7 may be substantially similar to that of FIGS. 2-6. The seat cushion 200 shown in FIG. 7 can have pin holes 202 instead of ribs 18 to facilitate heat transfer (e.g., cooling) during fabrication (e.g., injection molding) of the seat cushion 10. Similar to the ribs 18, however, the pin holes 202 are generally rigid and have a lower resiliency relative to the relief pockets 20, such that they do not deform to the same extent as the relief pocket 20 when a force equivalent to the user's weight is applied thereon. While not illustrated, the embodiments of FIG. 7 may also have other structural differences such as size, shape and location of the relief pockets 20, but may provide substantially the same amount of cushioning as the relief pockets 20 shown in FIGS. 2-6.

FIGS. 8-10 illustrate various views of a seat pan 220 and a seat cushion 230 according to another embodiment. The seat pan 220 and the seat cushion 230 can be substantially similar to the seat cushion 130, 10 and 200 illustrated in FIGS. 1, 2-6 and 7 respectively. The seat cushion 230 as illustrated in FIG. 8 can have a waterfall edge. For instance, the seat cushion 230 can be of dimensions so as to have a bottom surface contour that generally matches a top surface contour of the seat pan 220 (as is the case with seat cushions 130, 10 and 200). In addition, the depth 232 of the seat cushion 230 can be greater than the depth 234 of the seat pan 220. The seat cushion 230 therefore has a front edge 236 that extends past the front edge 238 of the seat pan 220.

Referring now to FIG. 9, portions of the seat cushion 230 can be cantilevered to provide relief to the back of a user's legs and reduce the chances of portions of the user's legs from being pinched. For instance, at least the front edge 236 of the seat cushion can be cantilevered relative to the seat pan 220. The seat pan 220 has a seat pan depth 234 and a seat pan width 239, and the seat cushion 230 has a seat cushion depth 232 and the seat cushion width 240. The seat pan width 239 generally equals the seat cushion width 240. For instance, the front edge 236 of the seat cushion extends over a substantial portion (e.g., at least 70%) of the front edge 238 of the seat pan. The seat pan depth 234 is generally less than the seat cushion depth 232. The seat pan width 239 and the seat cushion width 240 can be generally variable along the depthwise (e.g., front-back in the illustrated embodiment of FIG. 9) direction, but generally follow the same contour such that at any location in the depthwise direction, the seat pan width 239 equals the seat cushion width 240. Similarly, seat cushion depth 232 and the seat pan depth 234 can generally vary in the widthwise (e.g., right-left in the illustrated embodiment of FIG. 9) direction. In the embodiments of FIGS. 8-10 however, the seat pan depth 234 is generally less than the seat cushion depth 232 at any point on the widthwise direction. Further, the difference between the seat cushion depth 232 and the seat pan depth 234 can be defined as an offset distance 242. The offset distance 242 can be generally constant along the widthwise direction (e.g., between the right edge 244 and the left edge 246) in such embodiments except near the right edge 244 and the left edge 246 as shown in FIG. 9.

The offset distance 242 is generally non-zero, and in some examples, extends between about 15 millimeters and about 35 millimeters, and preferably about 20 millimeters and about 25 millimeters. In the illustrated embodiment, the offset distance 242 is about 30 millimeters. In some such cases, the offset distance 242 permits the front edge 236 of the seat cushion 230 to act as a cantilevered edge, as the seat cushion is made of a material such as injection molded EVA. Such embodiments provide optimal amount of relief to the back of a user's legs while generally supporting the user's weight thereon.

As perhaps best seen in FIG. 10, the seat pan 220 can generally conform to the shape of the seat cushion 230 and support the seat cushion 230. The seat pan 220 can be rigid relative to the seat cushion 230. Accordingly, the waterfall edge design of the seat cushion 230 can provide relief to portions of a user's legs when seated on the pivot seat 100. For instance, when a user is seated in the active seating posture (illustrated by the dashed lines in FIG. 1), the front edge 236 of the seat cushion 230 shown in FIGS. 8-10 (that extends past the front edge 238 of the seat pan 220) rests against the underside of a user's thighs. As the seat cushion 230 is resilient relative to the seat pan 220, the front edge 236 of the seat cushion 230 may not cause a pinch point on the underside of the user's thighs, and provide cushioning thereto when the user's body weight is rested on the seat cushion 230. The front edge 236 of the seat cushion 230 is therefore softer (e.g., more deformable) relative to the front edge 238 of the seat pan 220 when a user's weight is applied on the seat cushion 230.

With continued reference to FIGS. 9 and 10, the seat cushion 230 comprises a plurality of connectors 250 to interface with the seat pan 220. The connectors 250 of the seat cushion 230 can engage with complementary connectors 250 of the seat pan 220 so as to rigidly connect thereto. In the illustrated embodiment, the connectors 250 are ribs that protrude outward from a second surface 252 of the seat cushion 230. As seen in FIG. 10, the seat pan 220 can have apertures 262 that are sized and shaped to receive the ribs of the seat cushion 230. The apertures 262 are positioned such that when the ribs are pushed therethrough, the seat cushion 230 may not move with respect to the seat pan 220. Further, the position of the apertures 262 and the ribs can be positioned and oriented such that the front edge of the seat cushion 230 extends past the front edge of the seat pan 220 when the ribs 250 of the seat cushion 230 are pushed through the apertures 262 of the seat pan 220.

FIG. 11 illustrates a pivot seat 300 according to another embodiment. The pivot seat 300 can be substantially similar to the pivot seat 100 illustrated in FIG. 1. Referring to FIG. 11, the pivot seat 300 can be rotationally symmetric about a seat axis 302. Such embodiments permit the user to use the pivot seat in any rotational orientation about the seat axis 302. With continued reference to FIG. 11 and referencing the exploded perspective view of FIG. 12, the pivot seat 300 comprises a base 304. As is appreciable from FIGS. 11 and 12, the base 304 can have a non-planar portion 344 contacting a floor surface. For example, the base 304 can be hemispherical. Alternatively, the base 304 can be curved so as to have an apex that can contact the floor surface. The base 304 can thus pivot toward the floor surface, thereby permitting the user to assume an active seating posture.

Referring to FIGS. 11 and 12, the pivot seat 300 includes a seat post 306. The seat post 306 can be recessed within a seat body portion 308. The seat post 306 can include a first end 310, and a second end 312 opposite to the first end 310. The first end 310 of the seat post 306 can be connected to the base 304, and the second end 312 can be connected to a seat pan 320. The seat pan 320 can also optionally include a handle (illustrated as a loop in FIGS. 11 and 12) to permit a user to transport the seat to different locations.

The seat pan 320 can be disc-shaped and have a planar first surface 322 (e.g., top surface) on which a seat cushion 330 is positioned (e.g., attached adhesively, or by mechanical fasteners). The seat cushion 330 may have a contoured profile to permit selective cushioning of certain areas of a user's body (e.g., sitz bones), however, the seat pan 320 may not follow the contours the seat cushion 330. The seat pan 320 can be rigid relative to the seat cushion 330, and may thus act as a support surface for mounting the seat cushion 330.

FIGS. 13-15 illustrate various views of the seat cushion 330. The seat cushion 330 can be substantially rotationally symmetric about the seat axis 302, so as to permit the user to sit in any desired rotational orientation (e.g., 360 degrees about the seat axis 302). As described previously with respect to seat cushions 10, 200 and 230, the seat cushion 330 can be resilient relative to the seat pan 320 and contoured to selectively provide increased cushioning for the user's sitz bones.

In some such examples, the seat cushion 330 can have a central core 332. The central core 332 can be surrounded by a relief portion 336. The relief portion 336 can be surrounded by an outer portion 338. The seat cushion 330 can have a first surface 340 (e.g., top surface or an interior surface below the top surface) providing a seating surface for the user to sit on and a second surface 342 (e.g., bottom surface or an interior surface above the bottom surface) opposite to the first surface 340. The first surface 340 can be contoured such that a portion 344 of the first surface 340 corresponding to the central core 332 can be concave, and a portion 346 of the second surface 342 corresponding to the central core 332 can be convex or generally planar when viewed from a plane parallel to the seat axis 302 (e.g., when viewed from the front, as shown in FIG. 15, or from the sides lateral to the view shown in FIG. 15). Such contouring may facilitate ease of manufacturing (e.g., molding) the material (e.g., EVA foam) of the seat cushion 330.

The relief portion 336 can be rotationally symmetric so as to substantially surround the central core 332, which may permit cushioning of sitz bones regardless of the rotational orientation in which the user is seated. The relief portion 336 can also be contoured to provide selective cushioning. For instance, the relief portion 336 can be contoured such that it deforms to a greater extent when a user's weight acts on the relief portion 336, relative to the deformation of the central core 332 and/or the outer portion 338 when a force equivalent to the user's weight acts on the central core 332 and/or the outer portion 338.

The relief portion 336 can be sized and positioned so as to accommodate different user sizes and sitz bone spacing (e.g., as described with respect to FIGS. 3-6). Returning to FIGS. 14 and 15, the relief portion 336 can have a relief portion width 348 that can be between about 20% and about 70% of a representative dimension 350 (e.g., radius) of the seat cushion 330 to accommodate variability in sitz bone size and spacing, as described previously. Further, the seat cushion 330 can have an overall thickness 352 defined between a first extremity 354 on the first surface 340 and a second extremity 356 on the second surface 342. The first extremity 354 can be an uppermost point of the first surface 340 (e.g., top surface) and the second extremity 356 can be a lowermost point of the second surface 342 (e.g., bottom surface). A thickness 358 of the relief portion 336 can be between about 20% and about 70% of the overall thickness 352. In the illustrated embodiment, the thickness 358 of the relief portion 336 is about 50% of the overall thickness 352. Higher values of thickness 358 of the relief portion 336 may provide less cushioning, whereas lower values of thickness 358 of the relief portion 336 may lead to less support.

As noted above, the relief portion 336 can be contoured so as to provide selective cushioning of certain areas (e.g., sitz bones) of the user's lower body. In an example, the first surface 340 corresponding to the relief portion 336 can be generally convex when viewed from a plane parallel to the seat axis 302. Correspondingly, the second surface 342 at a location corresponding to the relief portion 336 can be generally convex when viewed from a plane parallel to the seat axis 302. The contouring of the first surface 340 can advantageously result in receiving, and thereby making contact with the sitz bones, which may often be the lowest portion of the user's lower body when in a seated posture. Such contouring may permit the relief portion 336 to advantageously deform to a greater extent relative to areas surrounding the relief portion 336 (e.g., central core 332 and outer portion 338) when a user's weight is placed thereon, as described with respect to similarly contoured seat cushion 10 shown in FIGS. 2-6.

Referring again to FIG. 15, the second surface 342 can have areas that separate the relief portion 336 from the central core 332. One such area can be contact portions 360, 362, 366 and 368 that are generally planar so as to contact a generally planar first surface 322 of the seat pan 320 (shown in FIG. 12). As is appreciable, the contact portions 360, 362, 366 and 368 can generally form a second extremity 356 of the second surface 342, and be generally coplanar with each other.

Advantageously, the seat cushion 330 can be formed as a unitary piece using injected molding a suitable material (e.g., EVA). Accordingly, the convex portions of the central core 332, the convex portions of the relief portion 336 and the contact portions 360 can be a single continuous surface contoured as described above.

Embodiments of the present disclosure provide several advantages. Seat cushions according to the disclosed embodiments provide selective cushioning such that the relief pockets provide cushioning to the sitz bones for the user which are frequently uncovered by the user's muscles (e.g., gluteus maximus) when the user is in a seated position. The seat cushions are made of injection molded EVA, which is durable and cost effective to fabricate. The seat cushions are of a generally unitary construction (e.g., made of a single piece) despite having selective or variable resiliency at various portions of the seat cushion, which reduces discomfort associated with seat cushions fabricated from several pieces of foam that are attached together. Further, the relief pockets of the seat cushions are sized to accommodate a variety of sitz bone spacing, and are fabricated from polymers that have a desired shape memory to accommodate a wide range of user weights without having to size the cushions for each individual user. Additionally, embodiments that include a waterfall edge design on the seat cushion additionally provide further cushioning of the underside of a user's thighs when seated in the active or upright position. Further, embodiments also permit the seat cushion to be used in any rotational orientation.

Various examples have been described. These and other examples are within the scope of the following claims. 

1. A seat cushion, comprising: a first surface providing a seating surface to sit on; and a second surface opposite to the first surface, the second surface having a pair of relief pockets, the relief pockets being configured to provide cushioning to a user's sitz bones received when the user is seated on the seating surface at a location corresponding to the relief pockets, the second surface having variable resiliency such that a resiliency of the relief pockets is different from a resiliency of areas of the second surface surrounding the relief pockets.
 2. The seat cushion of claim 1, wherein the relief pockets are adapted to receive a user's weight acting through the user's sitz bones when the user is seated on the seating surface, the relief pockets being deformable in response to the user's weight, the deformation of the relief pockets being greater than a deformation of the areas of the second surface surrounding the relief pockets, when a force equivalent to the user's weight is applied on the areas of the second surface surrounding the relief pockets.
 3. The seat cushion of claim 2, wherein the relief pockets have an initial shape when the user is not seated on the seating surface, the resiliency of the relief pockets permitting the relief pockets return to their initial shape once a user seated in the seating surface rises from the seating surface.
 4. The seat cushion of claim 2, wherein the areas surrounding the relief pockets have a deformation negligible relative to the deformation of the relief pockets, when the force equivalent to the user's weight is applied on the areas of the second surface surrounding the relief pockets.
 5. The seat cushion of claim 1, wherein the seat cushion is fabricated as a unitary piece by molding a polymer material.
 6. The seat cushion of claim 5, wherein the polymer material forms a closed-cell foam after fabrication of the seat cushion, the polymer material being ethylene-vinyl acetate.
 7. The seat cushion of claim 5, further comprising a plurality of ribs provided on the second surface, the plurality of ribs facilitating flow of polymer material and heat transfer during fabrication.
 8. A seat cushion, comprising: a first surface providing a seating surface to sit on; a second surface opposite to the first surface, the first surface and the second surface each being contoured so as to form: a central core defined about a seat axis, a relief portion extending radially around the seat axis so as to substantially surround the central core, the relief portion being configured to receive and provide cushioning to a user's sitz bones received when the user is seated on the seating surface, and an outer portion defined so as to surround the relief portion such that the relief portion is positioned radially between the central core and the outer portion, the relief portion being configured so as to be deformable when a user's weight is supported by the seating surface, the deformation of the relief portion being substantially greater than a deformation of the central core and/or the outer portion when a force equivalent to the user's weight is applied on the central core and/or the outer portion.
 9. The seat cushion of claim 8, wherein the seat cushion is rotationally symmetric about the seat axis.
 10. The seat cushion of claim 8, wherein the relief portion extends a 360 degrees surrounding the seat axis.
 11. The seat cushion of claim 8, wherein the seat cushion has a thickness, and the relief portion has a relief portion thickness, the relief portion thickness being between about 20% and about 70% of the thickness of the seat cushion.
 12. The seat cushion of claim 8, wherein the seat cushion is contoured such that the first surface corresponding to the corresponding to the central core being concave and a portion of the second surface corresponding to the central core being convex or generally planar when viewed from a plane parallel to the seat axis.
 13. The seat cushion of claim 8, wherein the seat cushion is contoured such that the first surface of the seat cushion at a location corresponding to the relief portion being generally convex and the second surface of the seat cushion at a location corresponding to the relief portion being generally convex when viewed from a plane parallel to the seat axis.
 14. The seat cushion of claim 8, wherein the relief portion having a relief portion width, and the seat cushion has a representative dimension, the relief portion width being between about 20% and about 70% of the representative dimension.
 15. The seat cushion of claim 14, wherein the seat cushion is disc-shaped and the representative dimension is a radius.
 16. A seat cushion, comprising: a first surface providing a seating surface to sit on; a second surface opposite to the first surface, the second surface having a relief portion, the relief portion being shaped and sized to selectively provide cushioning to a user's sitz bones received when the user is seated on the seating surface at a location corresponding to the relief portion, the selective cushioning provided by the relief portion to the user's sitz bones being greater than cushioning provided by areas other than the relief portion to portions of the user's body other than the sitz bones that are in contact with the seating surface.
 17. The seat cushion of claim 16, wherein the relief portion occupies an area of between about 10% and about 50% of a total surface area of the second surface.
 18. The seat cushion of claim 16, wherein the relief portion comprises a pair of relief pockets separated by a relief pocket spacing, the relief pockets having a generally asymmetrically shape, the relief pocket spacing corresponding to an average sitz bone spacing of an adult male or female user.
 19. The seat cushion of claim 18, wherein the relief pockets are of a size configured to accommodate a standard deviation of about +/−1 inch relative to the average sitz bone spacing of an adult male or female user.
 20. The seat cushion of claim 18, wherein the relief pockets have a depth of between about 5% and about 50% of an overall depth of the seat cushion, and a width of between about 5% and about 50% of an overall width of the seat cushion.
 21. The seat cushion of claim 18, wherein the relief pockets have a thickness of between about 20% and about 70% of an overall thickness of the seat cushion.
 22. The seat cushion of claim 21, wherein the thickness of the relief pockets being variable whereby, the thickness of the relief pockets being greater near a back edge of the seat cushion than the thickness of the relief pockets near a front edge of the seat cushion.
 23. The seat cushion according to claim 21, wherein the seat cushion is supported by and/or connected to a seat pan of a pivot seat, the seat cushion having a front edge that contacts a portion of a user's thigh when a user is seated thereon, and the front edge of the seat cushion extending past a front edge of the seat pan, the front edge of the seat cushion being cantilevered relative to the seat pan.
 24. The seat cushion of claim 23, wherein a substantial portion of the seat cushion is resilient with respect to the seat pan.
 25. The seat cushion of claim 23, further comprising a one or more connectors located on the second surface of the seat cushion to permit connection of the seat cushion to the seat pan.
 26. The seat cushion of claim 23, wherein the seat pan has a first surface contoured so as to generally conform to a contour of the second surface of the seat cushion.
 27. The seat cushion of claim 26, wherein the seat pan has a seat pan depth and a seat pan width, and the seat cushion has a seat cushion depth and a seat cushion width, wherein the seat pan width generally equals the seat cushion width, and the seat pan depth is generally less than the seat cushion depth.
 28. The seat cushion of claim 27, wherein a difference between the seat cushion depth and the seat pan depth being equal to an offset distance.
 29. The seat cushion of claim 28, wherein the offset distance is generally constant along a widthwise direction between a right edge and a left edge of the seat cushion, the right edge and the left edge each being lateral to the front edge of the seat cushion.
 30. The seat cushion of claim 23, wherein the seat pan has a generally planar first surface, and the seat cushion has a generally non-planar second surface. 